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Extranuclear inheritance
student: Nguyễn Liên Hương
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1.1Mitochonidria(mt)
What’s mitochonnidria?
Mitochonidria is a membrane-enclosed organelle found in most eukaryotic cell.These organelle range from 0.5 to 10 micrometers in diameter.
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1.1Mitochonidria(mt)
Function:
- provide the energy a cell
-they’re involed in a range of other processes
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1.1Mitochonidria(mt)
Mitochondria DNA(mtDAN):

-mtDNA is circular DNA, generally relatively small
-16-18kbp in mammals, 75kbp in yeast, 367 in Arabidopsis
-5-10 copies/organelle in vertebrates,20-40 in plant
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1.1Mitochonidria(mt)

-intron generally absent,small intergenic spaces in small mtDNAs,reverse in larger ones such as yeast
-genetic code similar but modified
-Encodes rRNAs, tRNAs and 13 polypeptides in humans
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1.1Mitochonidria(mt)
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1.1Mitochonidria(mt)
MtDNA of human:
The human mt genome is a circular DNA molecule of about 16kilobases.It encodes 37 genes: 13 for subunits of respiratory complexes I,III,IV and V; 22 for mitochondrial tRNA (for the 20 standard amino acids,plus an extra gene for leucine and serine), and 2 for rRNA.
One mt can contain 2 to 10 copies of its DNA
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1.2 chloroplas(cp)
What’s chloroplas?
Cp is organelle found in plant cell and other eukaryotic organisms that conduct photosynthesis.cp capture light energy to conserve free energy in the form toATP and reduce NADP to NADPH through a complex set of processes call photosynthesis.
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1.2 chloroplas(cp)
Function of cp :
-convert light energy into chemical energy.It use carbon dioxide,water and photosynthesis to make carbonhydrates.
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1.2 chloroplas(cp)
Chloroplas DNA(cpDNA)
-cpDNA have circular DNA and complete gene expression systerm
-cpDNA commonly 100-225 kbp in size
-no nucleosome but it has introns and large intergenic regions
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-multiple copies/organelle, recombination can occur
-encode rRNAs,tRNAs, protein(~70s ribosome) and other protein/enzyme
-typical number of gene is about 140, broken down as follows : 4 rRNA genes, 30 tRNA,90 protein-coding gene, 20 of which code photosynthesis and electron transport function.
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1.3 extranuclear inheritance
What is extranuclear inheritance?
extranuclear inheritance is the transmission of gene occur outside the nucleus.It is found in most eukaryotes and is commonly known to occur in cytoplasmic organelles such as mitochonria and chloroplasts or from cellular parasites like viruses or bacteria.
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1.3 extranuclear inheritance
Types of E.I:
-vegetative segregation: occur with cp and mt during mitotic cell divisions and results in daughter cell that contain a random sample of the parents cell’s oranelles.
-uniparental inheritance: occur in extranuclear genes when only parent contributes organellar DNA to the offspring.
-biparental inheritance:occur in extranuclear genes when both parent contributes organellar DNA to the offspring.It may be less common than uniparental E.I,and usually occurs in a permissible species only faction of the time.
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1.3 extranuclear inheritance
EI can thus be charecterized by 3 properties:
-the distribution does not follow Mendelian laws
-reciprocal crossings behave differently
-the genetic materal segregates during ontogenetic
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Organelle Heredity
Organelles Typically Show Maternal Inheritance
Different mitochondrial genotypes are inherited from the maternal ancestor alone in vertebrates.
Chloroplasts also exhibit this pattern of inheritance.
Organelle DNA from the male parent is occasionally found in zygotes.
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Organelle Heredity
Knowledge of Mitochondrial and Chloroplast DNA Helps Explain Organelle Heredity

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Maternal inheritance of cpDNA
Looked at inheritance of variegated leaves
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Some plants have different types of leaves on different branches.
Allow them to self pollinate and collect. Cross pollinate to check results.
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Regardless of the type of pollen that was used to fertilise the flowers:
•Branches with white leaves gave only white leaf progeny.
•Branches with green leaves gave only green progeny.
•Branches with variegated leaves gave green,white and variegated progeny.
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conclusion
• Phenotype does not depend on nuclear genotype (pollen not involved)
• Must be dependent on cytoplasm of female organs in the flower.
• Cytoplasmic inheritance.
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Leaf variegation
Caused by segregation of different types of
chloroplasts
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Today we know that the white patches are
caused by a mutation in chloroplast genes coding for chlorophyll pigments.
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Maternal inheritance of mtDNA

-All children inherit their mother’s mtDNA type
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Mitochondrial DNA Mutations
Human mitochondrial mutations resulting in disease phenotypes have been found:
Mutant mtDNA genomes are maintained in a heteroplasmic state but only cause the disease phenotype if they exceed a certain percentage of the mtDNAs present. Thus, the disease appears sporadic.
(Numbers indicate the percentage of mutant haplotypes)
Red individuals show the phenotype due to random changes in the percentage of mutant haplotypes present.
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Mitochondrial DNA Mutations

Human mitochondrial mutations resulting in disease phenotypes have been found:
All diseases resulting from changes in mitochondrial DNA are fundamentally the result of malfunctions of the respiratory chain or oxidative phosphorylation.
The phenotypic effects of mitochondrial mutations reflect the extent to which a tissue relies on oxidative phosphorylation; the central nervous system (CNS) is most sensitive, followed by skeletal muscle, heart muscle, kidney, and liver.
Some mitochondrial diseases are:
Leber`s hereditary optic neuropathy (LHON) - loss of vision and cardiac dysrhythmia.
Myoclonic epilepsy and ragged red fiber disease (MERRF) - CNS abnormalities and deficiencies of skeletal and cardiac muscle function.
Kearns-Sayre syndrome - neuromuscular symptoms including paralysis of eye muscles, dementia, and seizures.

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Mitochondrial DNA Mutations
Red fibers in muscle cells
due to the proliferation of
defective mitochondria.

This shows the result of
MERRF (myoclonic
epilepsy and ragged red
fiber disease), which is
due to a point mutation
in the mitochondrial
lysine tRNA (in 80% to
90% of MERRF cases -
there are also other
mitochondrial mutations
that cause MERRF)
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Made by: Nguyen Lien Huong
K52a biology
Thank You !